Earlier this month, the Director of National Intelligence released the fifth installment in a multi-decade forecasting project aimed at preparing the government for future challenges. Surveys of potential threats and opportunities have been released every four years since 1997, timed to coincide with the start of a new presidential administration. The latest report, prepared by the intelligence community's center for long-term strategic analysis, is full of warnings about how geopolitical developments, demographic trends and new technologies might threaten national security.

But nestled amidst all the usual dangers is the mention of something unexpected -- solar geomagnetic storms. The storms are bursts of energy produced by the Sun that disrupt the Earth's magnetic field. They happen fairly frequently, and if they are intense enough they can damage satellites, blackout radio signals, and damage electrical equipment. Now there is growing concern that a really big storm might collapse much of the global electric grid, particularly in places with long high-voltage transmission lines such as Australia, Canada, China and the United States. The intelligence assessment warns that, "until 'cures' are implemented, solar super-storms will pose a large-scale threat to the world's social and economic fabric."

Solar storms are a natural byproduct of the physical forces at work in the sun, and thus have been with us throughout human history. However, they are assuming greater significance as modern civilization has come to rely on electricity to power every facet of commerce and culture. The potential of such disturbances to disrupt electrical flows was first noticed during a particularly intense storm in 1859 -- so intense that geomagnetically induced currents arced from telegraph wires, shocked operators and started fires. The phenomenon was not widely noticed, though, because aside from the telegraph few other electrical innovations had appeared.

Things are different today. Electrical transmission lines and the devices they sustain are ubiquitous, meaning that a storm comparable in intensity to the 1859 event could potentially be one of the greatest catastrophes in recorded history. Studies funded by national laboratories have estimated that a powerful solar disturbance could knock out electrical service to over a hundred million people, causing trillions of dollars in damage. And because the industrial base for manufacturing the transformers and capacitors used in delivering electricity is relatively small, it could take months, maybe years, to fully restore service.

These consequences were explored in a series of simulations conducted by John Kappenman, one of the few authorities on how solar geomagnetic disruptions might upset the current electrical distribution system. A report Kappenman prepared in 2010 for the Oak Ridge National Laboratory presented a stark picture of the danger such storms pose: "Geomagnetic storm environments can develop instantaneously over large geographic footprints. They have the ability to essentially blanket the continent with an intense threat environment and... produce significant collateral damage to critical infrastructures."

This is not just a theoretical concept. In 1989, a relatively modest geomagnetic disturbance collapsed the electric grid in Quebec, depriving millions of users of electricity for several hours. Grid architectures are designed to work around single-point failures, but in the 1989 event there were 15 major failures in a few seconds across the regional grid, and that was more than the system could cope with. Kappenman notes that the local intensity of the storm that caused this large-scale failure was only a fraction of what the same storm visited on other, more isolated locales, and that other solar storms have produced much bigger disruptions of the Earth's magnetic field. For instance, a storm in 1921 is estimated to have been 10 times stronger.

The rapid expansion of the electrical grid in recent decades, coupled with the growing reliance of society on relatively fragile electrical devices, has greatly increased the danger posed by solar storms. Military planners understand the vulnerability of the grid to upset, but have been more concerned with man-made threats such as the electromagnetic pulse that would be generated by a high-altitude nuclear detonation. However, whereas the nuclear-burst scenario is a mere possibility, the frequent recurrence of solar storms is a certainty. The only reason a storm-driven catastrophe has not already occurred is that the vast majority of solar disturbances do not affect the area of space around the Earth, and even when they do the induced charges tend to be generated in areas where there is only modest electrical infrastructure.

Eventually, though, a really big solar storm will deliver its full fury on the American heartland, and then the accumulated design decisions that have been made as the domestic electrical grid expanded tenfold over the last half-century will lead to disaster. I can testify personally to the fragility of the local grid, because although I live in an upscale community within a few miles of the nation's capital -- a community populated with many influential people such as Supreme Court justices and corporate CEOs -- my home has experienced half a dozen prolonged losses of electricity this year alone. It turns out that most power companies just aren't very well equipped to deal with bad terrestrial weather, much less the kind of extra-terrestrial disturbance that a solar storm can produce. When everything goes down at once, calling for help from neighboring jurisdictions isn't a viable option.

Much has been written about how antiquated the U.S. electrical grid is -- the average substation transformer is 42 years old -- but according to John Kappenman, some of the newer technology is more vulnerable to geomagnetically induced upset than older systems. Higher-voltage transmission lines that have become more common in recent years are intrinsically more susceptible to upset, and those lines are largely concentrated in the manufacturing centers of the Midwest. Kappenman warned in his 2010 study that, "In contrast to well-conceived design standards that have been successfully applied for more conventional threats, no comprehensive design criteria have ever been considered to check the impact of the geomagnetic storm environments." In fact, he continues, "the design actions that have occurred over many decades have greatly escalated the dangers posed by these storm threats for this critical infrastructure."

Fortunately, many of the concepts and tools needed to mitigate the consequences of solar storm activity for the electrical grid exist today. Implementation of solutions could easily be included in efforts to modernize the grid, which are already long overdue in some places. But since few politicians or policymakers have noticed the danger posed by solar storms, there is a real possibility that sometime in the near future a sizable portion of the U.S. electrical grid could be knocked offline for months by a threat that many Americans don't even know exists.

I focus on the strategic, economic and business implications of defense spending as the Chief Operating Officer of the non-profit Lexington Institute and Chief Executive Officer of Source Associates. Prior to holding my present positions, I was Deputy Director of the Securi...